New research shows that the shark embryos can detect the bio-electric fields of approaching predators. When they do, they freeze by stopping their gill movements, as shown in the video below. This suggests that even at these early stages, embryonic sharks can recognise dangers and instinctively try to avoid them, say the researchers.

Staying still can be a good way of escaping the attention of hungry predators, as anyone who's seen the T. rex attack in Jurassic Park will know. But these sharks are positively precocious about it.